N.Z. Seismologists Study Wellington Quake Risk as City Re-Opens

By Matthew Brockett -
Jul 22, 2013

New Zealand seismologists are trying
to determine whether the magnitude 6.5 earthquake that struck
Wellington two days ago has increased the chances of a much
bigger rupture occurring under the capital city.

The July 21 tremor, which was centered offshore about 57
kilometers (35 miles) south-southwest of Wellington, was New
Zealand’s biggest earthquake since a magnitude 6.3 killed 185
people in the South Island city of Christchurch two years ago.
It may have transferred some stress onto a larger fault below
Wellington that’s capable of releasing quakes of magnitude 8 or
greater, GNS Science seismologist John Ristau said.

“It is possible, we have to do more study to get a precise
map of the stress pattern,” he said in an interview. “Having
said that, the most recent studies found that the probability of
a major earthquake along the Wellington fault is actually lower
than previously thought.”

Wellington re-opened for business today even as aftershocks
from the magnitude 6.5 quake continued to rattle the region. The
city was largely closed yesterday after the quake, which hit
shortly after 5 p.m. on Sunday evening, threw goods from store
shelves, blew out windows and caused people to run screaming
from buildings such as movie theaters. Four people were
hospitalized with minor injuries. There were no fatalities.

Just 35 of about 2,500 buildings in the central business
district sustained damage, Wellington Mayor Celia Wade-Brown
said last night. About 12 of them have been cordoned off due to
concerns about falling glass and masonry. Some office blocks,
including the Precinct Properties New Zealand Ltd.’s HP Tower,
remain closed while engineers check their structural soundness.

Statistics New Zealand delayed the release of a minor piece
of data today, and canceled a news conference scheduled for
tomorrow, citing water damage to its Wellington building.

There is a 7 percent chance of another magnitude 6 or
greater earthquake in the region in the next 24 hours, and a 19
percent risk of one hitting over the next seven days, Ristau
said.